Melatonin for Jet Lag and Shift Work: What the Evidence Supports

Short answer: Melatonin is a hormone your body already makes to signal sleep timing, and supplements may help reduce jet lag symptoms according to limited evidence from the NIH Office of Dietary Supplements (NIH ODS). Evidence that it meaningfully helps shift workers sleep is currently rated insufficient, meaning more research is needed before strong conclusions can be drawn.

What Melatonin Actually Does in the Body

Melatonin is a hormone produced by the pineal gland, a small structure in the brain. According to the NIH ODS, it has two closely linked roles: helping time the body's circadian rhythms (the roughly 24-hour internal clock) and signaling darkness to promote the onset of sleep. Production rises in the evening as light fades and falls again in the morning. Because of this light sensitivity, exposure to bright screens or overhead lighting at night can suppress your body's own melatonin output.

The NIH ODS rates the evidence that melatonin regulates circadian rhythm and sleep timing as strong. That foundational role is what makes it a logical candidate for situations where your internal clock is out of sync with local time, such as crossing multiple time zones or working overnight shifts.

Jet Lag: What the Research Shows

Jet lag happens when your internal clock is misaligned with the day-night cycle at your destination. Symptoms can include difficulty falling asleep, daytime fatigue, and trouble concentrating.

The NIH ODS rates evidence that melatonin supplements may help reduce symptoms of jet lag as limited. Limited evidence means some studies show a positive signal, but the body of research is not yet large or consistent enough to draw firm conclusions. It does not mean the evidence is negative, only that it is preliminary.

Practical considerations that come up in the research literature include:

• Direction of travel may matter. Eastward travel, which requires advancing your clock, is generally considered harder to adjust to than westward travel.
• The number of time zones crossed appears to influence how pronounced the misalignment is.
• Timing of the dose relative to the destination's sleep schedule is thought to be important, though optimal timing has not been definitively established for all travelers.

Because no adult target dose or upper limit has been established by dietary reference intake authorities, according to the NIH ODS, personal dosing decisions should be made with a clinician or pharmacist rather than based on general guidelines alone.

Shift Work: A More Complicated Picture

Shift workers face a recurring challenge: their required sleep window conflicts with the body's natural inclination to be awake during daylight hours. It might seem like melatonin would be a straightforward solution, but the NIH ODS currently rates evidence that melatonin helps shift workers sleep as insufficient. Insufficient evidence means the available research does not yet provide a reliable basis for conclusions in either direction.

This does not mean supplements are useless for every individual shift worker. It means the science has not yet produced the kind of consistent, well-controlled trial data needed to make a population-level recommendation. If you work rotating or overnight shifts and are considering melatonin, speaking with a sleep specialist or your primary care provider is a reasonable first step.

Other Sleep Conditions: Context for Comparison

Understanding where jet lag fits in the broader evidence picture is useful. For reference, the NIH ODS evidence ratings for other sleep-related uses are:

• Delayed sleep-wake phase disorder (DSWPD): limited evidence that melatonin may help people fall asleep sooner.
• Certain sleep problems in children: limited evidence that melatonin may improve time to fall asleep and total sleep duration.
• Chronic insomnia in adults: insufficient evidence that melatonin is an effective treatment.

These ratings help illustrate that melatonin's strongest research support is in circadian timing situations, such as jet lag and DSWPD, rather than in general insomnia.

Safety: What Is Known and What Is Not

According to the NIH ODS, short-term use of melatonin supplements appears to be safe for most people. However, there is not enough information on long-term safety, and at doses higher than the body normally produces, the overall safety picture is unclear. No adult upper limit has been established.

Reported side effects are generally mild and may include:

• Headache
• Dizziness
• Nausea
• Daytime sleepiness

Because melatonin can cause drowsiness, the NIH ODS advises avoiding driving or operating machinery after taking it.

As with all dietary supplements, melatonin supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA.

Drug and Substance Interactions

The NIH ODS identifies several clinically relevant interactions. Talk to a doctor before combining melatonin with any medication.

• Blood-thinning medicines (anticoagulants and antiplatelets, for example warfarin): A possible increased bleeding risk means people taking these drugs should use melatonin only under medical supervision.
• Antiseizure medicines (anticonvulsants): People with epilepsy should be under medical supervision, as melatonin may affect seizure control.
• Sedatives, sleep aids, and alcohol (for example benzodiazepines, zolpidem, eszopiclone): Combining these with melatonin may cause excessive sedation or drowsiness.
• CYP1A2 inhibitors such as fluvoxamine: Because melatonin is metabolized by the CYP1A2 enzyme, inhibitors of this enzyme can raise melatonin blood levels. Estrogens and certain quinolone antibiotics may also increase melatonin levels through similar pathways.

Practical Takeaways

The evidence base for melatonin is clearest for its core biological role in circadian timing, which is rated strong by the NIH ODS. Its application to jet lag carries a limited evidence rating, meaning early research is encouraging but not definitive. Its use for shift work remains in the insufficient category, calling for more research before broad recommendations are appropriate.

If you are considering melatonin for jet lag or shift work, the most useful steps are to review your current medications with a pharmacist or doctor before starting, discuss appropriate timing and amount with a clinician rather than relying on label suggestions, and keep use short-term until more long-term safety data become available.

Sources

All evidence ratings and safety information in this article are drawn from the NIH Office of Dietary Supplements and the National Center for Complementary and Integrative Health (NCCIH). This article is for informational purposes only and does not constitute medical advice.